Synthetic ponds for farmed fish function close to crop fields Saturday, April 19, 2025, at a Mainstream USA fish farm in Dateland, Arizona (AP Photograph/Joshua A. Bickel)
TUCSON, United States— Storks scatter, white towards blue water, as Dan Mohring’s pickup truck rumbles down the dust highway. He’s towing a trailer filled with ground-up beef, hen, fish and nutrient bits behind him, able to be shot out of a cannon into the ponds beneath.
It’s time to feed the fish.
Mohring fires up the machine and the meals flies out in a rainbow arc. Then the water comes alive. A whole bunch of beating, gobbling barramundi wiggle their strategy to the floor, all combating for a bit. Till, in a number of months, they may develop into meals themselves.
Within the desert of landlocked Arizona, the place the Colorado River disaster has put water use below a microscope, Mainstream Aquaculture has a fish farm the place it’s rising the tropical species barramundi, also referred to as Asian sea bass, for American eating places.
READ: 3 Western states suggest extra water cuts to save lots of Colorado River
Mainstream sees it as a sustainable various to ocean-caught seafood. They are saying cooks and acutely aware shoppers like that the meals has a shorter distance to journey, eliminating a few of the air pollution that comes from huge ships that transfer merchandise all over the world. They usually and a few aquaculture consultants argue it’s environment friendly to make use of the water twice, for the reason that nutrient-rich leftovers can irrigate crops like Bermuda grass bought for livestock feed.
“We’re within the enterprise of water,” mentioned Matt Mangan, head of Australia-based Mainstream’s American enterprise. “We need to be right here in 20 years’, 30 years’ time.”
Price the fee?
However some consultants query whether or not rising fish on a big scale in an arid area can work with out excessive environmental prices.
That query comes right down to what folks collectively resolve is an efficient use of water. In Arizona, some locations handle water extra aggressively than others. However the entire state is coping with the impacts of local weather change, which is making the area drier and water solely extra valuable.
The farm makes use of groundwater, not Colorado River water. It’s a nonrenewable useful resource, and like mining, totally different folks and industries have totally different philosophies about whether or not it ought to be extracted.
READ: US states wrestle to share dwindling waters of Colorado River
“So long as groundwater is handled as an open useful resource in these rural elements of Arizona, they’re vulnerable to new industries coming in and utilizing the groundwater for that business,” mentioned Sarah Porter, director of the Kyl Heart for Water Coverage at Arizona State College’s Morrison Institute.
Some scientists imagine aquaculture can play a job in defending wild ocean ecosystems from overfishing. And it’d play at the least a small position in smoothing any provide issues that end result from the Trump administration’s tariffs on imports from dozens of nations, together with those who ship the U.S. about 80 % of its seafood, per america Division of Agriculture.
Kevin Fitzsimmons holds a farmed tilapia Sunday, April 20, 2025, at a analysis lab in Tucson, Arizona. (AP Photograph/Joshua A. Bickel)
A two-for-one deal?
Within the greenhouses at College of Arizona professor Kevin Fitzsimmons’ lab in Tucson, tilapia circle idly in tanks that filter down into tubs filled with mussels and floating patches of collard greens and lettuce. Fitzsimmons mentored the scholar who began the tilapia farm finally purchased by Mainstream about three years in the past the place they now increase barramundi.
“I don’t assume desert agriculture goes away,” he mentioned. “Clearly, we need to do it as water-efficient as potential.”
However not everybody agrees it’s potential.
“Synthetic ponds within the desert are silly,” mentioned Jay Famiglietti, a professor at ASU and director of science for the Arizona Water Innovation Initiative. He frightened about heavy water losses to evaporation.
Mangan says that evaporation hasn’t been a difficulty a lot because the lack of warmth within the wintertime. That has required pumping extra water since its heat when it arrives on the floor helps hold the barramundi cozy. However Mangan says they’ve been enhancing pond design to retain warmth higher and have discovered, after the final 12 months of analysis and improvement, that they’ll reduce their water requirement by about half because of this.
Plus, he argues, the water popping out of the fish ponds is “basically liquid fertilizer,” and although it’s barely salty, they use it for crops that may tolerate it, like Bermuda grass dairy cows can eat.
However that’s supporting the cattle business, which contributes greater than its share of planet-warming greenhouse fuel emissions, Famiglietti mentioned.
“Doing two suboptimal issues doesn’t make it higher,” he mentioned.
Defining a ‘affordable’ use of groundwater, a finite useful resource
Purple flowers sprout alongside paddle wheels. Fish bones crunch underfoot. The faint odor of brackish water and ammonia catches within the breeze.
With out groundwater, none of it could be potential.
Some farmers in Arizona depend on water from the Colorado River, however many others use nicely water to irrigate crops like alfalfa for the dairy business or the lettuce, cucumbers and melons shipped nationwide year-round.
Arizona has seven areas across the state the place groundwater is rigorously managed. Dateland doesn’t fall into a type of, so the one rule that basically governs it’s a regulation saying if you happen to land personal there, you’ll be able to pump a “affordable” quantity of groundwater, mentioned Rhett Larson, who teaches water regulation at ASU.
What could be thought-about “affordable” relies upon from crop to crop, and there’s actually no precedent for aquaculture, an business that hasn’t but unfold commercially statewide.
Utilizing numbers offered by Mainstream, Porter calculated that the fish farm would demand a “very great amount” of water, on par with a giant ranch or probably much more than some suburbs of Phoenix. And he or she famous that though the water use is being maximized through the use of it twice, it’s nonetheless depleting the aquifer.
When the corporate scoped out Arizona to develop, Mangan mentioned they didn’t see practically the identical sorts of laws as again in Australia.
As a part of its development technique, Mainstream can be hoping to work with different farmers within the space so extra can use nutrient-rich fish pond wastewater to supply hay. They are saying a number of have expressed curiosity.
A substitute for wild-caught fish
The seafood business wants to cut back its reliance on catching small wild fish to feed greater farmed ones that people eat, mentioned Pallab Sarker, an assistant professor on the College of California, Santa Cruz, who research sustainability within the aquaculture business. He mentioned seabirds and mammals depend on small species like anchovies and mackerel generally utilized in fish meal.
“We must always not depend on ocean fish to develop fish for aquaculture to fulfill the demand for people,” Sarker mentioned.
Mainstream will get its fish feed from two suppliers, Skretting and Star Milling, however Mangan and Mohring mentioned they didn’t know for sure the place these suppliers obtained their base substances from.
Fitzsimmons, of the College of Arizona, additionally identified that between air pollution, overfishing and oceanfront improvement for recreation, the business fishing business had already been going through issues. He doesn’t assume that Trump’s strikes this spring to open up marine protected areas for business fishing will enhance that state of affairs the way in which aquaculture might.
“We are able to’t hold searching and gathering from the ocean,” Fitzsimmons mentioned.
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